Morris Dam, Concrete gravity dam in Los Angeles County, United States

The Morris Dam is a gravity structure that spans the San Gabriel River in Los Angeles County, rising 245 feet (75 meters) above the riverbed. It features a concrete overflow spillway designed to manage water flow during high-water periods.

Construction began in 1932 and finished in 1934, with former President Herbert Hoover attending the official dedication. This completion marked an important milestone in regional flood management infrastructure development.

The dam carries the name of Samuel Brooks Morris, who served as the chief engineer for the Pasadena Water Department during its construction. Locals and water professionals recognize it as an important piece of regional water management history.

The dam and reservoir lie along State Route 39 in the Angeles National Forest, a few miles northeast of Azusa. The crest stands at 1,161 feet (354 m) above sea level, while the reservoir reaches 1,152 feet (351 m) at maximum pool. The concrete foundations of the old naval test compound are visible from the highway. The spillway sits slightly north of the main structure.

The concrete foundations of the Morris Reservoir Naval Weapons Test Site, run with Caltech from 1943 to 1993, are still visible from State Route 39, which passes the dam. Most of the compound's buildings were demolished in the 1990s.